Small red dot on night pictures

Discussion in 'Digital Photography' started by Joshua Beall, Jul 6, 2004.

  1. Joshua Beall

    Joshua Beall Guest

    Hi everyone,

    I have noticed a small red dot on pretty much all the night pictures I have
    shot. It happens with both my 28-80 and my 75-300 lenses, so I do not think
    it is a lense problem. Also, I do not notice this shot except during night
    or dark shooting conditions. Even indoor lighting with no flash does not
    reveal this dot.

    I am shooting a Canon EOS 10D. Any ideas on what could cause this? What
    are the chances that there is a problem with the sensor? Could it be dust
    on the sensor? I have thought about opening the shutter and shining a
    flashlight on the sensor to see if I can see anything, but I do not want to
    damage the sensor by shining a bright light on it for an extended period of
    time. Should I be worried about this, or is a flashlight not bright enough
    to cause any harm?

    Here is a crop of an image that shows the dot:
    http://joshbeall.com/personal/redDot.jpg (41k)

    Here is the original shot. The dot is at (2093,1472):
    http://joshbeall.com/personal/moon.jpg (1.1m)

    Thoughts?

    Sincerely,
    -Josh
    Joshua Beall, Jul 6, 2004
    #1
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  2. Joshua Beall

    Ed Ruf Guest

    On Tue, 06 Jul 2004 15:16:50 GMT, in rec.photo.digital "Joshua Beall"
    <> wrote:

    >Hi everyone,
    >
    >I have noticed a small red dot on pretty much all the night pictures I have
    >shot. It happens with both my 28-80 and my 75-300 lenses, so I do not think
    >it is a lense problem. Also, I do not notice this shot except during night
    >or dark shooting conditions. Even indoor lighting with no flash does not
    >reveal this dot.
    >
    >I am shooting a Canon EOS 10D. Any ideas on what could cause this? What
    >are the chances that there is a problem with the sensor? Could it be dust
    >on the sensor? I have thought about opening the shutter and shining a
    >flashlight on the sensor to see if I can see anything, but I do not want to
    >damage the sensor by shining a bright light on it for an extended period of
    >time. Should I be worried about this, or is a flashlight not bright enough
    >to cause any harm?
    >
    >Here is a crop of an image that shows the dot:
    >http://joshbeall.com/personal/redDot.jpg (41k)
    >
    >Here is the original shot. The dot is at (2093,1472):
    >http://joshbeall.com/personal/moon.jpg (1.1m)


    Stuck pixel. If still under warranty send it in to have it mapped out.
    Maybe someone else can point to a user utility to do such as is
    available for some other makes/models.
    ________________________________________________________
    Ed Ruf Lifetime AMA# 344007 ()
    See images taken with my CP-990 and 5700 at
    http://EdwardGRuf.com
    Ed Ruf, Jul 6, 2004
    #2
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  3. Joshua Beall

    Joshua Beall Guest

    "Ed Ruf" <> wrote in message
    news:...
    > Stuck pixel. If still under warranty send it in to have it mapped out.
    > Maybe someone else can point to a user utility to do such as is
    > available for some other makes/models.


    Any idea why it would only show up on night shots?
    Joshua Beall, Jul 6, 2004
    #3
  4. Joshua Beall

    marlin Guest

    You have a hot pixel. This happens when a CCD is exposed for a long time.
    Some pixels (in your case 1) expose fast, so when you select a slow shutter
    speed, they show up as red dots. I'm kinda surprised about this in an E10D.
    How old is the camera? If it's within 1 year of purchasing (i.e. under
    warranty) you can send it to canon to remap the CCD.
    Richard
    "Joshua Beall" <> wrote in message
    news:CnzGc.24984$...
    > Hi everyone,
    >
    > I have noticed a small red dot on pretty much all the night pictures I

    have
    > shot. It happens with both my 28-80 and my 75-300 lenses, so I do not

    think
    > it is a lense problem. Also, I do not notice this shot except during

    night
    > or dark shooting conditions. Even indoor lighting with no flash does not
    > reveal this dot.
    >
    > I am shooting a Canon EOS 10D. Any ideas on what could cause this? What
    > are the chances that there is a problem with the sensor? Could it be dust
    > on the sensor? I have thought about opening the shutter and shining a
    > flashlight on the sensor to see if I can see anything, but I do not want

    to
    > damage the sensor by shining a bright light on it for an extended period

    of
    > time. Should I be worried about this, or is a flashlight not bright

    enough
    > to cause any harm?
    >
    > Here is a crop of an image that shows the dot:
    > http://joshbeall.com/personal/redDot.jpg (41k)
    >
    > Here is the original shot. The dot is at (2093,1472):
    > http://joshbeall.com/personal/moon.jpg (1.1m)
    >
    > Thoughts?
    >
    > Sincerely,
    > -Josh
    >
    >
    marlin, Jul 6, 2004
    #4
  5. Joshua Beall

    HooDooWitch Guest

    "Joshua Beall" <> somehow
    managed to post:

    >"Ed Ruf" <> wrote in message
    >news:...
    >> Stuck pixel. If still under warranty send it in to have it mapped out.
    >> Maybe someone else can point to a user utility to do such as is
    >> available for some other makes/models.

    >
    >Any idea why it would only show up on night shots?
    >

    It's probably there on all your shots, it's just that a longer
    exposure time makes it more prominent.

    To check, set camera to full manual, man.focus and 30 second exposure.
    Shoot in RAW format. Leave the lens cap on and take a picture. The red
    dot should be there.

    --
    HooDooWitch (NaCl - Gratis)

    http://www.usefilm.com/photographer/51251.html
    HooDooWitch, Jul 6, 2004
    #5
  6. Joshua Beall

    Joshua Beall Guest

    "marlin" <> wrote in message
    news:l_zGc.27254$...
    > You have a hot pixel. This happens when a CCD is exposed for a long time.
    > Some pixels (in your case 1) expose fast, so when you select a slow

    shutter
    > speed, they show up as red dots. I'm kinda surprised about this in an

    E10D.
    > How old is the camera? If it's within 1 year of purchasing (i.e. under
    > warranty) you can send it to canon to remap the CCD.


    It is less than a year old. I can still get it taken care of under warranty
    if need be. I think I will check with some local camera shops to see if
    they can get it repaired for me quickly, though, as I would rather not have
    to ship my camera off. I would be so lonesome without it... ;-)
    Joshua Beall, Jul 6, 2004
    #6
  7. Joshua Beall

    Mark Spacey Guest

    It is whats called in the trade as a HOT PIXLE, a pixle that registers
    hot under long exposores, no cure and they move around ! and usually
    appear on all black areas of the picture, just use photoshop to remove
    it, they all do it, canon 10 d is no bigger culprit than many other
    dslrs, the eos 1ds is a classic for hot pixles, !
    Mark Spacey, Jul 6, 2004
    #7
  8. Joshua Beall

    Mark Spacey Guest

    It is a hot pixle, they appear on time exposures in black areas, all
    canon slr do it, the eos 1ds is worst of all, it happens when a sensor
    becomes confused and registers hot, very easy to remove from images ,
    use the red eye tool in photoshop or similar,
    Not worth worrying about
    >
    Mark Spacey, Jul 6, 2004
    #8
  9. Journalist-North, Jul 6, 2004
    #9
  10. Joshua Beall

    Ryan Robbins Guest

    "Joshua Beall" <> wrote in message
    news:CnzGc.24984$...
    > Hi everyone,
    >
    > I have noticed a small red dot on pretty much all the night pictures I

    have
    > shot. It happens with both my 28-80 and my 75-300 lenses, so I do not

    think
    > it is a lense problem. Also, I do not notice this shot except during

    night
    > or dark shooting conditions. Even indoor lighting with no flash does not
    > reveal this dot.


    It appears to be a hot pixel, which is common on long exposures or at high
    ISO settings.
    Ryan Robbins, Jul 15, 2004
    #10
  11. Joshua Beall

    Mike Russell Guest

    Joshua,

    This is what's known as a "hot pixel" there may be utilities available for
    your specific camera that will fix them.
    --

    Mike Russell
    www.curvemeister.com
    www.geigy.2y.net

    Joshua Beall wrote:
    > Hi everyone,
    >
    > I have noticed a small red dot on pretty much all the night pictures
    > I have shot. It happens with both my 28-80 and my 75-300 lenses, so
    > I do not think it is a lense problem. Also, I do not notice this
    > shot except during night or dark shooting conditions. Even indoor
    > lighting with no flash does not reveal this dot.
    >
    > I am shooting a Canon EOS 10D. Any ideas on what could cause this?
    > What are the chances that there is a problem with the sensor? Could
    > it be dust on the sensor? I have thought about opening the shutter
    > and shining a flashlight on the sensor to see if I can see anything,
    > but I do not want to damage the sensor by shining a bright light on
    > it for an extended period of time. Should I be worried about this,
    > or is a flashlight not bright enough to cause any harm?
    >
    > Here is a crop of an image that shows the dot:
    > http://joshbeall.com/personal/redDot.jpg (41k)
    >
    > Here is the original shot. The dot is at (2093,1472):
    > http://joshbeall.com/personal/moon.jpg (1.1m)
    >
    > Thoughts?
    >
    > Sincerely,
    > -Josh
    Mike Russell, Jul 18, 2004
    #11
  12. Joshua Beall

    Hunt Guest

    In article <CnzGc.24984$>, jbeall@donotspam.
    remove.me.heraldic.us says...
    >
    >Hi everyone,
    >
    >I have noticed a small red dot on pretty much all the night pictures I have
    >shot. It happens with both my 28-80 and my 75-300 lenses, so I do not think
    >it is a lense problem. Also, I do not notice this shot except during night
    >or dark shooting conditions. Even indoor lighting with no flash does not
    >reveal this dot.
    >
    >I am shooting a Canon EOS 10D. Any ideas on what could cause this? What
    >are the chances that there is a problem with the sensor? Could it be dust
    >on the sensor? I have thought about opening the shutter and shining a
    >flashlight on the sensor to see if I can see anything, but I do not want to
    >damage the sensor by shining a bright light on it for an extended period of
    >time. Should I be worried about this, or is a flashlight not bright enough
    >to cause any harm?
    >
    >Here is a crop of an image that shows the dot:
    >http://joshbeall.com/personal/redDot.jpg (41k)
    >
    >Here is the original shot. The dot is at (2093,1472):
    >http://joshbeall.com/personal/moon.jpg (1.1m)
    >
    >Thoughts?


    Is it in the same place on all shots (where it is visible)? Looking at it in
    PS, it appears to be a bad pixel in sensor, but dust could yield the same
    look. Is camera in warranty? I hear (have no personal experience with it, as I
    use Nikon) that Canon will clean camera/sensor one time under warranty. Check
    with Canon dealer/repair facility.

    Baring that, if you know where to look on all images, PS, or any image editing
    program with a clone-type tool can easily take care of it.

    Hunt
    >
    >Sincerely,
    > -Josh
    >
    >
    Hunt, Sep 1, 2004
    #12
  13. Hunt wrote:
    >
    > In article <CnzGc.24984$>, jbeall@donotspam.
    > remove.me.heraldic.us says...
    > >
    > >Hi everyone,
    > >
    > >I have noticed a small red dot on pretty much all the night
    > >pictures I have shot. It happens with both my 28-80 and my
    > >75-300 lenses, so I do not think it is a lense problem. Also,
    > >I do not notice this shot except during night or dark shooting
    > >conditions. Even indoor lighting with no flash does not reveal
    > >this dot.
    > >

    >
    > Is it in the same place on all shots (where it is visible)? Looking
    > at it in PS, it appears to be a bad pixel in sensor, but dust could
    > yield the same look.


    I think dust would require much more than some scattered moonlight
    to make such a noticeably red dot.

    Josh, here's a suggestion. Set your camera on a table. Leave the
    lens cap on. Put the eyepiece cover on the camera so no light gets
    in that way, either. Take a one-second exposure (or however long
    you use when taking pictures at night). See if the red dot is there.

    If it is, you've most likely got a hot pixel. Since you don't seem
    to see it during indoor, no-flash lighting, I'd bet the hot pixel's
    dark current is significantly higher than the rest of the pixels.

    Take another picture with the lens cap and eyepiece cover on, but
    this time make the shutter speed something more like 1/60 second.
    See how bright the red dot is now. If it's dark current then the
    red dot should be dimmer since you're not accumulating as much of
    a "signal" with the shorter exposure. This would also explain why
    you don't see the red dot during non-nighttime exposures.

    If you're going to do a lot of night photography, it's pretty good
    practice to take a dark frame (i.e. lens cap on) at the same shutter
    speed and ISO settings as your regular exposures. Then you can
    digitally subtract the dark frame from your shots, significantly
    reducing the effect of dark noise. Some folks take multiple dark
    frames during their night photography sessions, particularly when
    the ambient air temperature changes rapidly.

    If the red dot is not there in the image taken with the lens cap
    and eyepiece cover on, it's more likely dust than a hot pixel.

    BJJB
    BillyJoeJimBob, Sep 2, 2004
    #13
  14. Joshua Beall

    Eddy Vortex Guest

    The quick fix that I use is a software app called "HotPixelKiller'. Works
    great and it's free. Do a search and you'll find it. Eddy
    "Hunt" <> wrote in message
    news:...
    > In article <CnzGc.24984$>, jbeall@donotspam.
    > remove.me.heraldic.us says...
    > >
    > >Hi everyone,
    > >
    > >I have noticed a small red dot on pretty much all the night pictures I

    have
    > >shot. It happens with both my 28-80 and my 75-300 lenses, so I do not

    think
    > >it is a lense problem. Also, I do not notice this shot except during

    night
    > >or dark shooting conditions. Even indoor lighting with no flash does not
    > >reveal this dot.
    > >
    > >I am shooting a Canon EOS 10D. Any ideas on what could cause this? What
    > >are the chances that there is a problem with the sensor? Could it be

    dust
    > >on the sensor? I have thought about opening the shutter and shining a
    > >flashlight on the sensor to see if I can see anything, but I do not want

    to
    > >damage the sensor by shining a bright light on it for an extended period

    of
    > >time. Should I be worried about this, or is a flashlight not bright

    enough
    > >to cause any harm?
    > >
    > >Here is a crop of an image that shows the dot:
    > >http://joshbeall.com/personal/redDot.jpg (41k)
    > >
    > >Here is the original shot. The dot is at (2093,1472):
    > >http://joshbeall.com/personal/moon.jpg (1.1m)
    > >
    > >Thoughts?

    >
    > Is it in the same place on all shots (where it is visible)? Looking at it

    in
    > PS, it appears to be a bad pixel in sensor, but dust could yield the same
    > look. Is camera in warranty? I hear (have no personal experience with it,

    as I
    > use Nikon) that Canon will clean camera/sensor one time under warranty.

    Check
    > with Canon dealer/repair facility.
    >
    > Baring that, if you know where to look on all images, PS, or any image

    editing
    > program with a clone-type tool can easily take care of it.
    >
    > Hunt
    > >
    > >Sincerely,
    > > -Josh
    > >
    > >

    >
    Eddy Vortex, Sep 2, 2004
    #14
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